Palladium Supported on Graphitic Carbon Nitride: An Efficient and Recyclable Heterogeneous Catalyst for Reduction of Nitroarenes and Suzuki Coupling Reaction

In this study, a novel platelet-like nanocatalyst, Pd/g-C 3 N 4 with easily approachable active sites, was developed. The mesoporous graphitic carbon nitride (g-C 3 N 4 ) is a layered structure connected by planar amino groups, which can work as stabilizer and active support for noble metal nanoparticles. The palladium nanoparticles with an average particle size of 3.25 nm were evenly dispersed on the surface of g-C 3 N 4 without aggregation. Detailed charaterizations reveal that there is no covalent-bond interaction between g-C 3 N 4 and Pd NPs. The Pd/g-C 3 N 4 catalyst showed excellent catalytic activity in the reduction of nitroarenes by NaBH 4 , and Suzuki coupling reaction of aryl halides with arylboronic acids under mild conditions. The reduction of 4-nitrophenol has a pseudo-first-order rate constant of 7.29 × 10 −3 s −1 , and an activity parameter of 1.37 s −1 mM −1 , which is higher than those reported in the literature. Furthermore, the Suzuki coupling reactions processed smoothly with 97.0 % isolate yield in less than 30 min in water with PEG600 as the additive. The catalyst could be recycled for five times without significant loss of catalytic activity, which confirmed the good stability of the catalyst. Graphical Abstract